This invention relates to anionic complex containing nitrogen, phosphorus, oxygen, and aluminum in the anion, to a new process for the manufacture thereof, and to fire extingishing compositions containing such complexes.
Much of the knowledge gained in the age-long struggle to minimize the devastating effects of fire can be summed up by recalling that fire is extinguished by chilling a combustible material to a temperature below the necessary for the combustion chain reaction to be sustained, and by interfering with the access of oxygen to the combustible material. Water, the nearly universal extinguishing agent, works by way of both of these effects.
The classic soda and acid fire extinguisher and many of the aqueous foam delivery systems that have been developed intensify the smothering or oxygen access blocking effect of a non-combustible gas such as nitrogen, carbon dioxide, and steam while sacrificing some of the chilling effect owing to the diminished mass of water being projected at the burning material.
There have been attempts to increase the efficiency of water as an extinguishing agent by increasing its wetting power. "Wetter water", which is water containing dissolved surface-active materials, is more efficient on an equal weight or volume basis than water alone; it is, however, more viscous than pure water and therefore the advantage of greater fire extinguishing efficiency of a given quantity of water is counterbalanced by the diminished volume of "wetter water" actually delivered on burning material in a given time by given equipment, as well as by the need to have a specially prepared composition ready for instant use. With this come additional problems such as the increased tendency to corrode metals by surface active agent solutions which can lead to blocked valves and nozzles and failures of the system to deliver extinquishing liquid when needed. Furthermore, to the extent that the additives are compounds of hydrogen and carbon, fuel is actually being fed into the fire by such extinguishing material. A recent example of this approach to extinguishing fire with water and surface active material is disclosed in A. Globus U.S. Pat. No 3,979,302 of Sept. 7, 1976. The additive is a poly(complex) of a hydrated condensation reaction of a mono- or dialkanolamine with a higher fatty acid. There have been many materials disclosed that while chemically dissimilar work in a similar way, so that a detailed listing of individual disclosures can be omitted for brevity's sake.
Non-aqueous fire extinguishing agents are also known. Sand and a variety of "dry chemical" solids function by smothering a fire, sometimes reinforcing this effect by releasing a non-combustible gas, such as carbon dioxide from sodium bicarbonate or ammonia from diammonium phosphate. While nearly any non-combustible anhydrous fluid can at least temporarily extinguish a fire, the choice in practice is limited to compressed carbon dioxide and relatively few others. The high degree of toxicity of carbon tetrachloride and its combustion product phosgene has caused the use of carbon tetrachloride fire extinguishers to be abandoned and the use of other halogenated organic compounds to be under suspicion or restricted.
A recent disclosure of a non-aqueous fire extinguishing composition is by H. Filter in U.S. Pat. No. 3,972,820 of Aug. 3, 1976. Filter's composition can be considered a kind of projectile in which the material that actually extinguishes a fire represents 25 to 85 weight percent of the composition, preferably 35 to 60 weight percent, and is a halogenated organic compound, while the remainder of the composition is a combination of an oxidizer and a binder, with optionally a curing catalyst. In the heat of a fire the ingredients are caused to interact to generate vapors of the halogen compound under pressure and direct these at the fire, in order to extinguish it.
Anhydrous fire extinguishing compositions that do not require halogen compounds include urea melted and mixed with sodium, potassium, or ammonium carbonate, bicarbonate, or other salts at 130.degree.-150.degree. C under pressure, cooled, and powdered for use as a dry chemical extinguisher or a fire preventing coating, by J. Birchall in U.S. Pat. No. 3,484,372 of Dec. 16, 1969. Dry chemical extinguishers also complement high-expansion foams in fighting liquified natural gas fires according to L. Brown in Chemical Abstracts volume 83 (1975), 208187n.
For a more extensive review of the art of extinguishing fires, the prior art references cited by Filter and the article by C. Babcock in "Kirk-Othmer Encyclopedia of Chemical Technology" second edition (A. Standen, executive editor; Wiley-Interscience, New York 1966) volume 9, pages 286-299 can be consulted.
To minimize fire damage, many attempts have been made to diminish the flammability of various useful material by including in or with them substances capable of extinguishing a fire if it should occur. Such substances can be termed fires retardant or fire preventing agent or compositions, and their use cutomarily accompanies the use of combustible natural and synthetic polymers such as wood, paper, cotton, and other useful forms of cellulose; polyamid and polyester synthetic fibers and cloth manufactured therefrom; rubber, polyurethane, and plasticized polyvinyl chloride foams; ethylene, propylene, butylene, and styrene polymer plastics and fibers, and the like.
A useful fire preventing composition must be affect the useful properites of articles treated therewith as little as possible. This reasonable and plausible requirement is actually quite difficult to satisfy since in the most useful combustible materials quite large quantities of the conventional fire preventing compositions must be used to accomplish the desired protection, and this inevitably changes the overall composition and therefore the properties of the treated items. Thus fabrics tend to be stiffened, foams to be made less resillient, and plastics to be discolored as a result of the incorporation of conventional fire preventing compositions in the required concentrations, and even where these primary properties are acceptable, other properties such as odor, toxicity, and cost are sometimes adversely affected. The art of fire prevention in useful materials by the use of added fire preventing compositions has been reviewed by R. Hindersinn in "Encyclopedia of Polymer Science and Technology" (N. Bikales, executive editor, Wiley-Interscience, New York 1967) volume 6 pages 1-64, and for textiles by B. Drake, Jr. in "Kirk-Othmer Encyclopedia", second edition, volume 9, pages 300-315.
Representative disclosures of fire preventing compositions applied to wood include the use of urea-formaldehyde resin with boric acid or a borate salt by H. Chase in U.S. Pat. No. 3,438,847 of Apr. 15, 1969; phosphoric acid with diammonium phosphate or with urea and dicyandiamide to a recommeded 3% P content for protecting wood fiberboard, by A. Leonovich et al in articles abstracted in Chemical Abstracts volume 70 (1969) 79310c, volume 71 (1969) 31561d, and volume 74 (1971) 32834a; hardboard treated with ammonium phosphate, bromide, or sulfamate, guanidine phosphate, or borax and boric acid, by I. Hirato in Chemical Abstracts volume 70 (1969), 12779u; borax and boric acid mixed with ammonium phosphate and sodium pentachlorophenate by T. C. Hsieh in Chemical Abstracts volume 73 (1970) 132172z; sodium or ammonium bromide to a 6 to 7.5% by weight of dry wood add-on along with urea-formaldehyde or any of ammonium phosphate, sulfate or sulfamate or sodium phosphate or boric acid by M. Lewin in Israeli U.S. Pat. No. 27,503 of Sept. 17, 1970; borax and urea with a water soluble vinyl alcohol polymer and a polyhdric alcohol by E. Degginger in U.S. Pat. No. 3,537,873 of Nov. 3, 1970; any one or more of ammonium phosphate, boric acid, borax, and urea with an inert water-resistant coating for wood boards pressed from wood pulp by Stlftelsen Wallboards Industriens Forkningsinstitut in British Pat. No. 1,242, 290 of Aug. 11, 1971; 5 to 50% by weight reaction products of boric acid with a nitrogen compound such as urea, thiourea, or dicyandiamide at 60.degree.-155.degree. C in molar ratios from 1 to 0.5 to 1 to 3 by K. Kawakami in Japanese Pat. 73/23399 of July 13, 1973; borax and urea-formaldehyde resin in flame-resistant particleboard by D. Cartlidge in U.S. Pat. No. 3,873,662 of Mar. 25, 1975; sodium polyborate at 3 to 13% by weight in fire resistant particleboard along with dicyandiamide or malamine and formaldehyde by L. Surdyk in U.S. Pat. No. 3,874,990 of Apr. 1, 1975; and aqueous solutions of partially reacted monomethyloldicyandiamide, melamine, and phosphoric acid with molar ratios monomethyloldicyandiamide to melamine from about 11.5 to 1 to about 3 to 1, and phosphoric acid to the two nitrogen compounds together from about 1 to 1 to about 1.5 by W. Oberly in U.S. Pat. No. 3,986,881 of Oct. 19, 1976.
Representative disclosures of fire preventing compositions applied to paper include an impregnating bath containing an acrylic resin, ammonium bromide, and urea or dicyandiamide disclosed by W. Mayer in U.S. Pat. No. 3,667,999 of June 6, 1972; corrugated paperboards impregnated with boric acid and aluminum sulfate adhered to foamed polystyrene by Y. Kimura in Japanese Kokai 75/79,586 of June 28, 1975; and the impregnation of unsized paper of 62 grams per square meter weight with an aqueous solution of starch, urea, and ammonium phosphate to a weight of 80 grams per square meter or a 22.5% dry add on, by J. Sheen in German published application 2,404,790 of Aug. 14, 1975.
Representative disclosures of fire preventing compositions applied to plastic and elastomer foams include kaolin or a mixture of urea and sodium silicofluoride to make an acetone-formaldehyde resin foam fire-resistant by T. Waag in British Pat. No. 1,158,698; mixtures of urea with thiourea or ammonium thiocyanate to protect polyvinyl alcohol foam by B. Lawes in U.S. Pat. No. 3,481,886 of Dec. 2, 1969; synthetic resin foams of polyvinyl chloride or polyethylene with boric oxide or borates. aluminum oxide and/or phosphate, and optionally chromic anhydride, pearlite, or ammonium phosphate, by J. Kimura in Japanese Kokais 75/86561, 86562, and 86563 of July 11, 1975; boric acid along with melamine and alumina hydrate in hydrophilic polyurethane foam by C. Kehr in U.S. Pat. No. 3,897,372 of July 29, 1975.
Representative disclosures in the field of fire preventing compositions applied to textiles and fabrics include the application of a amido compounds of cyanuric acid as salts of phosphoric acid, pyrohposphoric acid, or oxalic acid by F. Pollak in U.S. Pat. No. 2,418,525 of Apr. 8, 1947. Pollak's preferred amido compound is melamine. The textiles and fabrics are first impregnated with the acid and afterwards passed through a melamine bath, which forms an insoluble precipitate that strongly adheres to the fibers but can be removed by washing or similar water treatment. To diminish this water solubility the textiles and fabrics are treated or coated with a urea or thiourea condensation product with formaldehyde or mixtures thereof, and dried at 120.degree.-140.degree. C. Boric acid and dichlorodhydrin can be included to assist with the formation of the resinous condensation product. F. Ford in U.S. Pat. Nos. 2,482,755 and 2,482,756 of Sept. 27, 1949 disclosed treatment of a cellulosic textile with a strong acid, such as phosphoric acid; a soluble organic nitrogen containing base, such as urea, dicyandiamide guanidine carbonate, and aminoguanidine carbonate to act as a buffer and diminish tenderizing of the cellulose by the acid; formaldehyde or similar agent to combine with the organic nitrogen compound and the cellulose and thereby introduce more nitrogen into the compound or compounds produced on heat curing, with consequent increase in buffering action; and a volatile base such as ammonium hydroxide, dimethylamine or ethylenediamine, whose function is to stabilize the treatment solution against undesirable interactions of its components during use and subsequently volatilize to permit the acidic conditions that promote cure to develop on the fabric. With sufficient add-on of Ford's composition to the fabric and a sufficiently vigorous cure, fabric with good flame resistance that is maintained through a hot water washing or soaping operation is obtained. The required add-on is of the order of 100% wet pick up of a solution containing 30% by weight active ingredients.
Ford's composition and method with elaborations and variations in detail has remained popular, as shown by many subsequent disclosures. Thus K. Katsuura in Chemical Abstracts volume 67 (1967) 55078v disclosed a variant of the pad and and cure process with urea and phosphoric acid as flameproofing treatment for cotton fabrics whereby an organic solvent is used. Similarly, A. Benarous in French Patent 1,462,192 of Dec. 16, 1966 disclosed a variant where methylclorocorm solvent is used in a treatment with a fire preventing mixture consisting of urea, ammonium borate and bromide, phosphoric acid, ammonium hydroxide, tricresyl phosphate and emulsifier. L. Teodorescu in Romanian Patent 51,226 of Aug. 17, 1968 disclosed an emulsification method to combine the diammonium phosphate + urea system with the organic halogen compound (chlorinated paraffin and polyvinyl chloride) + antimony oxide system. D. Zyzka in Polish Patent 56,436 of Feb. 25, 1969 disclosed cotton treated by an impregnating bath of monosodium acid phosphate, urea, and a formaldehyde-melamine or formaldehyde-urea condensation product, followed by drying above 150.degree. C and then treating with aqueous ammonium chloride. R. LeBlanc in U.S. Pat. No. 3,899,483 of Aug. 12, 1975 disclosed a special aftertreatment with heavy metal and transition metal salts, especially titanium chlorides, of textiles which had been treated with organic or inorganic phosphorus compound fire preventing agents. The aftertreatment with the metal salt minimizes the loss in fire preventing ability caused in treated materials by ion exchange with the so-called hard water ions, particularly calcium and magnesium, and thereby increases the wash resistance of the fire preventing effect of the treated fabric.
Another important fire preventing composition and method that has gained a certain acceptance for treating cotton fabrics uses tetrakis(hydroxymethyl) phosphonium chloride ( abbreviated THPC) as the key chemical ingredient as disclosed by J. Guthrie et al in "American Dystuff Reporter" volume 44 No. 10 of May 9, 1955 pages P328 to P332, and U.S. Pat. No. 2,772,188 Nov. 27, 1956. In the processing of cotton fabrics, THPC is mixed with triethanolamine, methylolmelamine, and urea in aqueous solution. The solution is applied to fabric with a padder. The fabric is then dried at a relatively low temperature, for example 80.degree.-90.degree. C., and cured at an elevated temperature such as 135.degree.-150.degree. C, and finally washed and given a softening treatment. With a dry weight add-on of 16.6%, fabric passes the standard vertical flame test but with some afterflame, especially along cut edges and a 20% add-on is recommended by the authors for the fabric to show little or no afterflame when tested with a match. In subsequent elaborations and variants of this system, J. Beninate et al described a pad-dry-cure process for cotton fabrics using tetrakis(hydroxymethyl) phosphonium hydroxide together with urea and trimethylolamine (see Textile Research Journal volume 38 (1968), pages 267-272). R. Cole in German published application 2,009,121 of Jan. 28, 1971 applied the THPC-urea-trimethylolmelamine composition to wool at pH 4 to 5. J. Dipietro et al in Textile Research Journal volume 41 (1971) pages 593-599 compared the THPCurea-trimethylolmelamine composition to tris(2,3-dibromopropyl) phosphate, finding the former effective on cotton but ineffective on polyester and polyester-cotton blends while dibromopropyl phosphate was effective on both kinds of fabric. B. Aycock in U.S. Pat. No. 3,765,837 of Oct. 16, 1973 disclosed a combination of THPC with an allylurea compound for padding on polyester-cotton blend textile and subsequent bromination by soaking in a chloroform solution of bromine. Aycock's dry weight add-on was 21% before bromination. T. Tanisho in Japenese Kokai 75/63299 of May 29, 1975 disclosed a reaction product of THPC with urea and sodium hydroxide used to fireproof fabrics of polyvinyl alcohol in combination with phosphoric acid. D. Donaldson disclosed the addition of polyvinyl bromide to the THPC urea system to impart excellent flame resistance to 50-50 polyester-cotton blends, see Fire Retardant Chemicals, volume 2 No. 2 supplement (1975), pages 102-109. E. Stossel in U. S. Pat. No. 3,414,374 of Dec. 3, 1968 has disclosed neutral water soluble or colloidally soluble ionic complexes having phosphorus, oxygen, nitrogen and aluminum and/or chromium in an anionic portion of the molecule. The complexes are assigned the empirical formula ##STR1## In this formula, R.sub.1 is hydrogen, or an organic radical having one to about thirty carbon atoms. Me is aluminum or chromium, alone, or in a mixture with each other, and/or with any metal other than the alkali or alkaline earth metals. Such additional metal is added in a minor proportion, in substitution for part of the aluminum, and/or chromium, which constitute the major proportion. n is a number within the range from 0.1 to about 3, preferably from 0.25 to 2. w is a number within the range of 0 to about 100, preferably 0.5 to 2. p is at least equal to 1, preferably is above 3. Normally, p is within the range from about (1.5 to about 100. r is a number within the range from 1 to 2. h is a number in the range from 0 to (4-n). x is the valence to the anion, and will have a value determined by the preceding variables. It is always negative, and is in no way critical. The value of y is at least 1 and can range up to 20,000 or higher and is also not critical.
The complexes are described as resinous materials soluble in an equal volume of water. When applied to paper or wood they dry rapidly to form a glossy coating that does not embrittle during long service life and, when formed on cellulosic material, increase flame resistance. The complexes can be mixed with pigments and water to give concentrated dispersions useful as fire retardant paints. The complexes described in this patent are prepared by the reaction of concentrated solution of an aluminum or chromium acid phosphate with a compound having at least one -NHR.sub.2 group, where R.sub.2 is hydrogen or an organic radical or a phosphoro-oxygen radial. The simplest -NHR.sub.2 compound is ammonia. A special and preferred technique permits the reaction to be carried out simply and at atmospheric pressure if the volatile amine compound (e.g. ammonia) is formed during the reaction from a non-volatile compound (e.g. urea) which decomposes to yield the volatile amine compound under the reaction conditions. It is particularly desirable for some uses if the second product resulting from this decomposition is a gas. The disclosure of U.S. Pat. No. 3,414,374 also includes the reaction of phosphoric acid with a minor amount of boric acid to form a soft jelly which is then carried through the remaining steps of the process.
E. Stossel in U.S. Pat. No. 3,667,903 of June 6, 1972 has disclosed a foam polymerization process in which bubbles of foam being generated by the controlled decomposition of a blowing agent at a suitable temperature, for example urea in the range of 150.degree. to 225.degree. C, function of pressure vessels, of which the polymer forming reactants consitute the walls, thereby facilitating the transfer of heat, reacting materials, and volatile by-products into and out of the reacting mass. Stossel's foam polymerization process is well suited to the preparation of the ionic complexes disclosed in U.S. Pat. No. 3,414,374 when sufficient urea is used to act both as blowing agent for the foam polymerization and as reactant for the formation of the ionic complex.
E. Stossel in U.S. Pat. No. 3,945,987 of Mar. 23, 1976 has disclosed that concentrated solutions of acid aluminum phosphate can be neutralized with ammonia without precipitation when the viscous acid aluminum phosphate solution in water is mixed with substantially solid urea at a temperature not exceeding about 90.degree. C. to form a "clathrate" or urea adduct. The adduct is produced when an aluminum phosphate solution in aqueous phosphoric acid is concentrated until a semi-plastic highly viscous solution is obtained which contains between 10 to 12% water. This highly viscous fluid is then cooled to below 90.degree. C and, in a second step, intimately admixed with solid urea to form a urea adduct comples. Urea is added until a sample does not undergo precipitation when treated with concentrated ammonia. The urea inclusion complex is very fluid and contains about 7% of water. The fluid solution can be neutralized by ammonia gas to the required pH to form a mixture of the clathrate and ammonium phosphates.
The buffered, acid solution of the above described aluminum acid phosphate-urea clathrate and the neutralized mixture thereof with ammonium phosphates can be directly used for the impregnation of flammable materials as wood, paper, textiles, plastic foams, etc.
When the concentrated solution of the acid aluminum phosphate-urea clathrate is heated above a temperature of 150.degree. C, a voluminous foam is formed which contains within its innumerable cells encapsulated carbon dioxide. Upon heating, the urea of the "host molecule" decomposes into carbon dioxide and ammonia, the latter reacting with the aluminum phosphate of the foam bubble skins.